Liquid crystal displays (LCD) are widely used flat panel displays. Image display is achieved mainly by an LCD switch modulating light field intensity of a backlight resource. The LCD display includes a thin film transistor (TFT) device. In a thin film transistor liquid crystal display (TFT-LCD), each liquid crystal pixel on such a display device is driven by a thin film transistor integrated therebehind. Therefore, the TFT-LCD has a high response speed, high brightness, high contrast, small size, low power consumption, no radiation, etc., and is dominant in the current display market.
A film structural diagram of a thin film transistor array substrate in a prior art is as shown in FIG. 1. The array substrate includes a substrate 101, a buffer layer 102, an active layer 103, a gate insulation layer 104, a gate layer 105, an active metal layer 106, an interlayer insulation layer 107, a source/drain layer 108, and a passivation layer 109.
In the prior art, by depositing an active metal layer 106 on the gate layer 105 and reacting the active metal 106 with a portion of the active layer by a high temperature annealing process, the active metal layer 106 reacts with oxygen in the active layer 103 to form a corresponding metal oxide, and the active layer generates oxygen vacancies due to oxygen elements being lost, thereby reducing resistance of the active layer 103, so that the portion of the active layer where the reaction occurs is converted from a semiconductor into a conductor. A via hole is formed in the interlayer insulation layer in the array substrate, such that the source/drain region 108 is electrically connected to the portion of the active layer through the via hole in the interlayer insulation layer. Sometimes, due to errors of the annealing process or the relatively thick active metal film, the remaining active metal does not completely react to form a metal oxide, so that the gate 105, the gate insulation layer 104, and the active layer are electrically connected to form a leakage path between the gate 105 and the active layer 106, due to the active metal film.